System, method, and computer program product for ordering a plurality of write commands associated with a storage device

ABSTRACT

A system, method, and computer program product are provided for ordering a plurality of write commands associated with a storage device. In operation, a plurality of write commands associated with a storage device to be sent to a device are identified. Additionally, an order of the plurality of write commands is determined, the determined order being known by the device. Further, the plurality of write commands are ordered in the determined order.

FIELD OF THE INVENTION

The present invention relates to storage devices, and more particularly to ordering write commands associated with such storage devices.

BACKGROUND

Storage systems may include many devices including storage device and other devices connected to and/or in communication with the storage devices. These devices in communication with the storage devices often need to access commands and/or data associated with the storage devices. In many different types of storage systems, commands are queued and the commands are executed in a random order.

The Serial ATA (SATA) computer bus is one storage-interface for connecting host bus adapters to storage devices such as hard disk drives and optical drives, etc. Currently, in SATA systems and other comparable systems, commands are queued and the order that the commands are executed is random. A device connected to a SATA drive does not have any knowledge as to the order the write commands will be executed.

Thus, the device attached to a SATA drive may not pre-fetch write data unless it has enough resources to pre-fetch write data for all of the commands. Pre-fetching for all commands is very costly because pre-fetching all commands requires the use of a large portion of memory. Additionally, this pre-fetching may not add performance because the command being executed may not necessarily be the command for which data has been pre-fetched. There is thus a need for addressing these and/or other issues associated with the prior art.

SUMMARY

A system, method, and computer program product are provided for ordering a plurality of write commands associated with a storage device. In operation, a plurality of write commands associated with a storage device to be sent to a device are identified. Additionally, an order of the plurality of write commands is determined, the determined order being known by the device. Further, the plurality of write commands are ordered in the determined order.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a method for ordering a plurality of write commands associated with a storage device, in accordance with one embodiment.

FIG. 2 shows a system for ordering a plurality of write commands associated with a storage device, in accordance with one embodiment.

FIG. 3 shows a method for ordering a plurality of write commands associated with a storage device, in accordance with another embodiment.

FIG. 4 illustrates an exemplary system in which the various architecture and/or functionality of the various previous embodiments may be implemented.

DETAILED DESCRIPTION

FIG. 1 shows a method 100 for ordering a plurality of write commands associated with a storage device, in accordance with one embodiment. As shown, a plurality of write commands associated with a storage device to be sent to a device are identified. See operation 102.

In the context of the present description, a storage device refers to any device capable of storing data. For example, in various embodiments, the storage device may include, but is not limited to, a Serial ATA (SATA) drive, a Serial Attached SCSI (SAS) drive, a Fibre Channel (FC) drive, or a Universal Serial Bus (USB) drive, and/or any other storage device. Additionally, in various embodiments, the storage device may include a Peripheral Component Interconnect (PCI) or PCI Express based plug in card configured to appear as a storage device, or a PCI or PCI Express interface configured to appear as a storage device. In one embodiment, a PCI or PCI Express interface may be used to access the storage device.

Further, the write commands may be sent to any type of device capable of receiving commands. For example, in various embodiments, the device may include a host system, an SAS/SATA bridge (e.g. an SAS to SATA bridge, etc.), a USB/SATA bridge (e.g. a USB to SATA bridge, etc.), an FC/SATA bridge (e.g. an FC to SATA bridge, etc.), a PCI or PCI Express based plug in card (e.g. configured to appear as a storage device, etc.), a PCI or PCI Express interface, an interface used to access at least one storage device or system, or any device capable of having a plurality of commands outstanding at one time.

In addition to identifying the write commands associated with the storage device, an order of the plurality of write commands is determined, the determined order being known by the device. See operation 104. In one embodiment, the determined order may be a predetermined order known by the device.

As an option, the order may be determined based on an order in which the write commands are identified (e.g. a first come first served based approach, etc.). For example, as commands are generated and/or received, the commands may be queued. As another option, the order may include a predetermined order known by the device.

Of course, the order may include any order known by the device. In one embodiment, a controller may inform the device of the order. In this case, the order may be determined by the storage device in real time or near real time.

Further, the plurality of write commands are ordered in the determined order. See operation 106. In this case, the storage device may order the plurality of write commands in the determined order.

In this way, the device may be permitted to pre-fetch data associated with the plurality of write commands. In this case, the device may be permitted to pre-fetch the data before an associated write command is executed. This may be accomplished because the device knows the order of the write commands.

In one embodiment, read commands associated with the storage device may also be identified. In this case, the plurality of read commands associated with the storage device may be ordered randomly or in a determined order. In either case, the read commands may be intermixed with the write commands, where the write commands maintain their determined order relative to one another.

More illustrative information will now be set forth regarding various optional architectures and features with which the foregoing framework may or may not be implemented, per the desires of the user. It should be strongly noted that the following information is set forth for illustrative purposes and should not be construed as limiting in any manner. Any of the following features may be optionally incorporated with or without the exclusion of other features described.

FIG. 2 shows a system 200 for ordering a plurality of write commands associated with a storage device, in accordance with one embodiment. As an option, the present system 200 may be implemented to carry out the method 100 of FIG. 2. Of course, however, the system 200 may be implemented in any desired environment. It should also be noted that the aforementioned definitions may apply during the present description.

As shown, the system 200 includes a storage device 202. As shown further, one or more devices 204 are in communication with and/or connected to the storage device 202. This communication and/or connection may be accomplished utilizing any type of bus, etc.

In this case, the storage device 202 may represent any number of storage devices. For example, in various embodiments, the storage device 202 may represent a SATA drive, an SAS drive, an FC drive, a USB drive, a PCI or PCI Express based plug in card configured to appear as a storage device, and/or any other storage device.

Furthermore, the one or more devices 204 may include any device capable of receiving commands. For example, in various embodiments, the devices 204 may include an SAS/SATA bridge, a USB/SATA bridge, an FC/SATA bridge, a PCI or PCI Express based plug in card, an expander, and initiator, and/or any other device.

In operation, the storage device 202 may identify write commands associated with the storage device 202 to be sent to one or more of the devices 204. The storage device 202 may then determine an order. In various embodiments, this determination may be made in real time or near real time, or may be a predetermined order.

The storage device 202 may then order the write commands in a determined order, where the determined order is known by the devices 204. In one embodiment, the storage device 202 may order the write commands by placing the write commands in a queue in the order. In another embodiment, the storage device 202 may order the write commands by assigning an order to the write commands.

In one embodiment, the identifying, determining, and ordering may be performed based on a mode of the storage device 202. For example, a mode may indicate that a particular ordering is to be performed and/or utilized. In another embodiment, the identifying, determining, and ordering may be performed as a standard function.

In one embodiment, a plurality of read commands associated with the storage device 202 may also be identified. In this case, the plurality of read commands associated with the storage device 202 may be ordered randomly. Further, the plurality of read commands ordered randomly may be intermixed with the plurality of write commands in the determined order.

In this way, the devices 204 may be permitted to pre-fetch data associated with the write commands. In this case, the devices 204 may be permitted to pre-fetch the data before an associated write command is executed. This may be accomplished because the devices 204 know the order of the write commands.

For example, in some systems, a device (e.g. a host/bridge, etc.) attached to a SATA drive may not know the order of the write commands. Thus, the drive can not pre-fetch write data unless it has enough resources to pre-fetch write data for all the commands. However, pre-fetching for all commands may be very costly since this costs a large portion of memory.

As an option, a hard disk drive (HDD) may reorder the commands to reduce the number of rotations of the media needed to fetch all the data. Additionally, a solid-state drive (SSD) may reorder the commands based on the internal architectures to optimize for the drive. However, in some cases, the host/bridge attached to the drive that needs to fetch write data may be a bottle neck.

Thus, the drive may order the commands in a deterministic fashion which is known by the host and/or bridge. In one embodiment, this may be implemented as a first come first served approach. Thus, the host will know the order of the write commands and it may pre-fetch write data before the command is executed. In various embodiments, the drive may always perform this ordering, or the ordering may be based on a mode. As an option, there may be more than one mode.

Additionally, the ordering may be implemented for any protocol or mode within a protocol that does not have a deterministic technique of ordering the commands relative to one another. It should be noted that the order of the read commands may or may not be deterministic relative to the order of the write commands.

For example, many read and write commands may be received. The read commands may be ordered randomly and the write commands may be ordered deterministically. The read and write commands may be intermixed, where the relative order of the write commands to one another is maintained. It should also be noted that, in one embodiment, a memory controller (e.g. an SSD controller, etc.) may pass information about the order of write commands to the device attached to the drive to allow for efficient pre-fetching.

FIG. 3 shows a method 300 for ordering a plurality of write commands associated with a storage device, in accordance with another embodiment. As an option, the present method 300 may be implemented in the context of the functionality and architecture of FIGS. 1-2. Of course, however, the method 300 may be carried out in any desired environment. Again, the aforementioned definitions may apply during the present description.

As shown, it is determined whether a command is identified. See operation 302. If a command is identified, it is determined whether the command is a read command. See operation 304.

If the command is a read command, the read command is queued in a random order. See operation 306. If the command is not a read command, it is determined if the command is a write command. See operation 308.

If the command is a write command, the command is queued in an order known to a receiving device. See operation 310. For example, in one embodiment, the write command may be queued in an order and then the receiving device may be informed as to the order. In another embodiment, the write command may be queued in a predetermined order already known by the receiving device.

It is then determined whether a command to pre-fetch data is received from a receiving device. See operation 312. If a command to pre-fetch data is received, the data is sent. See operation 314.

In one embodiment, a SATA drive may execute write commands in the same order that a host, bridge, or attached device sends the commands. The host, bridge, or attached device may then pre-fetch data based on knowing the order the write commands will be executed. Thus, all available write data storage may be used for the next data.

In this way, performance may be greatly increased since the write data may be pre-fetched before the device is ready for the write data. In one embodiment, an SSD controller may pass information about the order of write commands to the device attached to allow for efficient pre-fetching.

FIG. 4 illustrates an exemplary system 400 in which the various architecture and/or functionality of the various previous embodiments may be implemented. As shown, a system 400 is provided including at least one host processor 401 which is connected to a communication bus 402. The system 400 also includes a main memory 404. Control logic (software) and data are stored in the main memory 404 which may take the form of random access memory (RAM).

The system 400 also includes a graphics processor 406 and a display 408, i.e. a computer monitor. In one embodiment, the graphics processor 406 may include a plurality of shader modules, a rasterization module, etc. Each of the foregoing modules may even be situated on a single semiconductor platform to form a graphics processing unit (GPU).

In the present description, a single semiconductor platform may refer to a sole unitary semiconductor-based integrated circuit or chip. It should be noted that the term single semiconductor platform may also refer to multi-chip modules with increased connectivity which simulate on-chip operation, and make substantial improvements over utilizing a conventional central processing unit (CPU) and bus implementation. Of course, the various modules may also be situated separately or in various combinations of semiconductor platforms per the desires of the user.

The system 400 may also include a secondary storage 410. The secondary storage 410 includes, for example, a hard disk drive and/or a removable storage drive, representing a floppy disk drive, a magnetic tape drive, a compact disk drive, etc. The removable storage drive reads from and/or writes to a removable storage unit in a well known manner.

Computer programs, or computer control logic algorithms, may be stored in the main memory 404 and/or the secondary storage 410. Such computer programs, when executed, enable the system 400 to perform various functions. Memory 404, storage 410 and/or any other storage are possible examples of computer-readable media.

In one embodiment, the architecture and/or functionality of the various previous figures may be implemented in the context of the host processor graphics processor 406, an integrated circuit (not shown) that is capable of at least a portion of the capabilities of both the host processor 401 and the graphics processor 406, a chipset (i.e. a group of integrated circuits designed to work and sold as a unit for performing related functions, etc.), and/or any other integrated circuit for that matter.

Still yet, the architecture and/or functionality of the various previous figures may be implemented in the context of a general computer system, a circuit board system, a game console system dedicated for entertainment purposes, an application-specific system, and/or any other desired system. For example, the system 400 may take the form of a desktop computer, lap-top computer, and/or any other type of logic. Still yet, the system 400 may take the form of various other devices including, but not limited to, a personal digital assistant (PDA) device, a mobile phone device, a television, etc.

Further, while not shown, the system 400 may be coupled to a network [e.g. a telecommunications network, local area network (LAN), wireless network, wide area network (WAN) such as the Internet, peer-to-peer network, cable network, etc.] for communication purposes.

While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. 

1. A method, comprising: identifying a plurality of write commands associated with a storage device to be sent to a device; determining an order of the plurality of write commands, the determined order being known by the device; and ordering the plurality of write commands in the determined order.
 2. The method of claim 1, wherein the determined order is a predetermined order known by the device.
 3. The method of claim 1, wherein the order is determined based on an order in which the plurality of write commands are identified.
 4. The method of claim 1, further comprising permitting the device to pre-fetch data associated with the plurality of write commands.
 5. The method of claim 4, wherein the device is permitted to pre-fetch the data before an associated write command is executed.
 6. The method of claim 1, wherein the identifying, determining, and ordering are performed based on a mode of the storage device.
 7. The method of claim 1, wherein the storage device orders the plurality of write commands in the determined order.
 8. The method of claim 1, wherein the device includes a host system.
 9. The method of claim 1, wherein the device includes an SAS/SATA bridge.
 10. The method of claim 1, wherein the device includes a USB/SATA bridge.
 11. The method of claim 1, wherein the device includes an FC/SATA bridge.
 12. The method of claim 1, wherein the device includes one of a PCI or PCI Express based plug in card.
 13. The method of claim 1, wherein the device includes one of a PCI or PCI Express interface.
 14. The method of claim 1, wherein the device includes an interface used to access at least one storage device or system.
 15. The method of claim 1, wherein the device includes a device capable of having a plurality of commands outstanding at one time.
 16. The method of claim 1, further comprising identifying a plurality of read commands associated with the storage device.
 17. The method of claim 16, wherein the plurality of read commands associated with the storage device are ordered randomly.
 18. The method of claim 17, wherein the plurality of read commands ordered randomly are intermixed with the plurality of write commands in the determined order.
 19. The method of claim 1, wherein the storage device includes one of a Serial ATA (SATA) drive, a Serial Attached SCSI (SAS) drive, a Fibre Channel (FC) drive, or a Universal Serial Bus (USB) drive.
 20. The method of claim 1, wherein the storage device includes one of a PCI or PCI Express based plug in card configured to appear as a storage device.
 21. The method of claim 1, wherein the storage device includes one of a PCI or PCI Express interface configured to appear as a storage device.
 22. The method of claim 1, wherein a PCI or PCI Express interface is used to access the storage device.
 23. A computer program product embodied on a computer readable medium, comprising: computer code for identifying a plurality of write commands associated with a storage device to be sent to a device; computer code for determining an order of the plurality of write commands, the determined order being known by the device; and computer code for ordering the plurality of write commands in the determined order.
 24. An apparatus, comprising: a storage device for identifying a plurality of write commands associated with the storage device to be sent to a device, and for ordering the plurality of write commands in a determined order, the determined order being known by the device. 